With recent changes in life styles, the consumption of sanitary articles and paper diapers is steadily increasing. Most water absorbents, moisture absorbents or humectants and thickening agents used in sanitary articles and paper diapers are based on synthetic high polymer materials. Since currently available sanitary articles and paper diapers are of a disposable type, they are disposed of in flush toilets and discharged into the environment. However, they are essentially not biodegradable and therefore remain in the environment for a prolonged period of time. This is not only unseemly but also deleterious to the environment. Thus, the development of alternatives that are biodegradable and which are hence compatible with the maintenance of a healthy environment is strongly desired.
Similarly, with recent advances in biotechnology, attempts have been made to incorporate biomaterials in cosmetics. However, the use of such "biocosmetics" is very limited and there has been a growing need for the development of new organism-derived moisture absorbents or humectants that can be used as a base for cosmetics.
Desertification is an environmental problem affecting the ecology of the entire earth. Japan is making a contribution to the greening of deserts by supplying Egypt and other such countries with synthetic high polymer water absorbents, moisture absorbents and humectants for use to retain water for irrigating seedlings. If such water absorbents, moisture absorbents or humectants are organism-derived and are biodegradable and compatible with the environment, no harm results from their use in the growing of seedlings.
However, microorganism-derived biopolymers are usually expensive, in comparison with synthetic high polymers, thereby limiting the range of their utilization. In addition, there are many cases wherein synthetic high polymers are formed into various shapes after they have been dissolved or dispersed in organic solvents in commercial production. Accordingly, it is a general consideration that if microorganism-derived biopolymers are treated with an organic solvent, such functions will be impaired. Hence, the range of their application has been generally limited. If such biodegradable biopolymers which are compatible with the environment are treated with an organic solvent without any deterioration in their functions resulting therefrom, application could be envisaged in various fields, including the field of chemical industries and their use will be remarkably advantageous.
Accordingly, in order for biopolymers to be formed in various shapes and to have a wide range of applications, it is essential that their properties should not be caused to deteriorate after they are dissolved or dispersed in organic solvents broadly used in the field of chemical industries. Thus, the biopolymers have come to be used as starting materials for products in various chemical industries.
The object of the present invention therefore is to provide a polymer containing a polysaccharide that overcomes and eliminates the problems associated with synthetic high polymer water absorbents, moisture absorbents or humectants and which, hence, is highly biodegradable and can be used without adversely affecting the environment giving problems such as secondary pollution and which, in addition, has a high water absorption capability, moisture absorption capability, moisture retention capability and thickening capability, having resistance to organic solvents.
With respect to the fermentation and production of polysaccharides, methods using saccharides (fructose and sucrose), inorganic materials and natural medium components (concretely, yeast extracts) have been reported (Japanese Patent Public Disclosure No. 291292/1990).
It has also been found that said polysaccharides can be fermented and produced by adding fructose, sucrose and glucose as saccharides to natural medium components such as yeast extracts, polypeptone and CSL. It is anticipated that when natural medium components are used, components may become unhomogeneous and hence the fermentation and production of said polysaccharides may become unstable. The present inventors have conducted studies and aimed at establishing synthetic mediums which contain no natural component, are cheap to produce and have good workability. As a result, they have found that said polysaccharides can be fermented and produced by synthetic mediums comprising a saccharide, an inorganic salt, an amino acid mixed solution and a trace metal salt mixed solution. It is another object of the present invention to determine their conditions.